The invention relates generally to a disk-hub connection and more specifically to disc-hub connectors for utility vehicle disc brakes.
According to the state of the art, disk-hub connections for disk brakes of motor vehicles are constructed either in one piece--that is, the disk and the hub set consist, for example, of one casting--or--see, for example, German Patent Document DE 34 41 304 concerning the above-mentioned type--of two pieces. Because of expansion and crack problems as the result of an intensive heating of the disks during the braking, the one-piece constructions are mainly suitable for lighter motor vehicles. With an increasing trend to use disk brakes also in heavy utility vehicles, the demand exists for a disk construction which can also securely withstand the high stresses occurring during a braking of heavy utility vehicles. Because of a lower tendency to form cracks, the two-piece variant has recently been favored. First attempts to adapt the technology shown in German Patent Document DE 34 41 304 (having the problem of poor ventilation and cooling) to the utility vehicle field are known, for example, from Patent Document WO93/14947. However, the disk shown there can be implemented with respect to manufacturing techniques only at relatively high cost.
In addition to the high requirements concerning the stability with respect to cracks, it is necessary in the case of disk-hub connections for utility vehicles to get by with the scarce available space. In the ideal case, a two-piece construction should not require more installation space than the corresponding one-piece variant.
From German Patent Document DE 34 36 729, as the closest state of the art, a disk-hub connection is known for connecting a brake disk with a hub, particularly for cranes of different types, whose brake disk is provided in the inner peripheral region with semicircular bores or recesses so that "support elements" are formed between the bores which project radially to the inside. On its outer periphery, the hub is also provided with semicircular recesses so that the hub has "cams" on it outer peripheral region which project radially to the outside. In this case, intermediate elements are used for the torque transmission between the hub and the disk as follows: When the hub and the disk are assembled (for example, by shrinking the disk onto the hub), the semicircular recesses of the hub and the disk are in each case situated opposite one another so that circular recesses are formed between the hub and the disk. Sleeves are inserted into these recesses, which sleeves are axially secured by screws and washers. Although it is possible in this manner to partly eliminate excessive strains result from temperature differences between the hub and the disk, the mounting of the disk remains relatively complicated. The solution is also hardly suitable for transmitting the high braking forces occurring in the case of faster utility vehicles.
In contrast to this state of the art, it is an object of the invention to provide a hub-disk connection which ensures a secure force transmission between the hub and the disk and can easily be mounted also in a narrow installation space.
The invention achieves this goal by a disk-hub connection in the case of which the torque transmission between the disk and the hub during braking from a forward drive and a reverse drive is always fully ensured. In the case of which, because of the uncoupling of the disk and the hub, crack formations caused by the heating of the disk during the braking operation are safely prevented. Furthermore, a disk-hub connection is implemented at reasonable cost whose components can be produced also without high-precision manufacturing tolerances and which can be assembled in an easy and rapid fashion. Another advantage of the invention is the fact that it does not increase the installation measurements of the disk-hub complex in comparison to a one-piece variant.
The use of additional elements between the disk and the hub, which also contribute to the torque transmission between the brake disk and the brake hub, is basically known (for example, from German Patent Document DE-OS 38 14 614 concerning rail vehicle technology), in the field of rail vehicle technology. But of the clearly lower frictional connection between the wheel and the rail, the braking torques are much lower than in the utility vehicle field. Thus, in the case of a multi-part construction of the hub and the disk, the bolts connecting the disk and the hub can also contribute to the transmission of the torque. For this reason, among others, only three intermediate sliding block elements are used in the case of the brake disk of German Patent Document DE OS 38 14 614. In contrast, because of the engagement of the cams of the hub in the intermediate element, the present invention makes it possible to also transmit larger torques securely and without the danger of breakage. The intermediate element implements a form closure and frictional connection which permits an unlimited secure transmission of the forces and torques between the disk and the hub which occur during the braking operations.
A preferred variant of the invention is characterized in that the intermediate elements engage in the supporting elements and are supported in the peripheral direction in a form-locking manner on the support elements. The variant of the invention implemented in this fashion further optimizes the torque transmission from the hub to the disk while simultaneously minimizing the required installation space because the cams, the intermediate elements and the wheel hub projection each engage in one another in a particularly space-saving manner.
In the case of another, particularly preferred embodiment of the invention, the intermediate elements have lateral projections which are supported in the axial direction on the support elements. In addition to taking over the task of the torque transmission in the radial direction, the support elements therefore advantageously also take over the required axial fixing of the disk on the hub.
Another advantage of the invention is the result of the fact that, because of the intermediate piece, it is possible to design the support surfaces such that the hub and the disk can be manufactured of different materials, which leads to further savings of weight and cost.
In the following, the invention will be described in detail with reference to the drawing. Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.